1. Field of the Invention
This invention relates to a dye composition for keratinous fibers, and, more particularly, to a dye composition for keratinous fibers which is capable of dyeing keratinous fibers to a strong tone. The present invention also relates to a novel 3,5-diaminopyridine derivative which is useful as a developing substance for said dye composition and to an intermediate for producing the 3,5-diaminopyridine derivative.
2. Description of the Background Art
Oxidizing dyes, in which a developing substance and a coupling substance are employed in combination, have been widely used for dyeing keratinous fibers such as hair or the like. These oxidizing dyes make use of oxidizing coloring substances produced by the oxidizing-coupling reaction of a developing substance and a coupling substance for strongly dyeing keratinous fibers such as hair or the like. Paraphenylenediamine derivatives, p-aminophenol derivatives, diaminopyridine derivatives, 4-aminopyrazolone derivatives, hetero-cyclic hydrazone, and the like are used as the developing substance. Given as the coupling substances which are used are o-naphthol, o-cresol, m-cresol, 2,6-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, benzcatechin, pyrogallol, 1,5-dihydroxynaphthalene, 1,7-dihydroxy-naphthalene, 5-amino-2-methylphenol, hydroquinone, 2,4-diaminoanisole, m-toluylenediamine, o-aminophenol, resorcin, resorcinmonomethylether, m-phenylenediamine, 1-phenyl-3-methyl-5-pyrazolone, 1-phenyl-3-amino-5-pyrazolone, 1-phenyl-3,5-diketopyrazolidine, 1-methyl-7-dimethylamino-4-hydroxyquinolone-2, 1-amino-3-cyanacetylamino-4-nitrobenzole, m-aminophenol, 4-chlororesorcin, 2-methylresorcin, 2,4-diaminophenoxyethanol, 2,6-diaminopyridine, 3,5-diaminotrifluoromethylbenzene, 2,4-diamino-6-hydroxypyrimidine, 2,4,6-triaminopyrimidine, 2-amino-4,6-diamino-2-hydroxypyrimidine, p-nitro-o-phenylenediamine, 2-amino-5-nitrophenol, p-nitro-m-phenylenediamine, o-nitro-p-phenylenediamine, 2-amino-4-nitrophenol, and the like.
These conventional oxidizing dyes have defects in their performance which are yet to be satisfied in terms of saturation or vividness of colors, dyeing capab ility, and fastness. Since these characteristics of oxidizing dyes are greatly affected by the coupling substances, it is extremely important to develop a coupling substance having superior characteristics to obtain a good oxidizing dye.
Among conventional blue color oxidizing dyes those in which m-phenylenediamine or 2,6-diaminopyridine is used as a coupling subsantce are known to give a blue color with high vividness. These dyes, however, involve remarkable color changes after the dyeing and discoloration due to shampooing. There has been a strong desire for the development of a dye composition for keratinous fibers giving an excellent vivid blue color and superior fastness.
In view of this situation, the present inventors have synthesized a variety of compounds and investigated their performance as a coupling substance. As a result, the inventors found that a specific type of 3,5-diaminopyridine derivatives or their salts satisfied the above requirement in a coupling substance. This finding has led to the completion of this invention.